One way of building and extending flavor is through the use of stocks. But let me say right away that, on a daily basis, I’d rather make a dish that doesn’t need a stock; because, like you, I’m busy. Still, stocks don’t have to be especially time-consuming.
My most frequent approach is the quick stock—a thin stock based on the trimmings of the vegetables used in a soup or whatever dish I’m making, plus maybe a bay leaf or other appropriate herb.
It’s a stock that cooks in 25 minutes at most. It doesn’t have the quality of a broth, but it does underscore the flavors already being featured in a dish.
I’ve seen chef’s recipes that really break the bank, calling for many very expensive vegetables for a few cups of stock. I’m sure it’s delicious, but that’s not my general intent. I tend to make a stock that merely reflects the ingredients in the dish it will be used in.
Here are a few general tips for making stocks:
what goes in
Think imaginatively about what you can use. Corncobs stripped of their kernels; chard stems; the skins, seeds, and strings from winter squash; a handful of lentils or almonds; celery root peelings; and the roots and leaves of leeks are all great sources of flavor. Herb stems, beans and bean broth, miso, soy sauce in small amounts, eggplant, lettuce (!).
If you’re not sure about how an ingredient works, boil some separately for fifteen minutes or so to see if you like the results. Some foods can turn grassy or bitter or just not be very good. Others might be surprisingly fine—like eggplant.
A stock is not a catchall for old or spoiled vegetables. A mushroom that’s dried or opened is fine; one that’s slimy is not. A limp carrot is okay; a moldy one is not. My policy: If I’m in doubt, I throw it out.
Chop your stock vegetables, because the more surface area that’s exposed to the water, the more quickly the vegetables will yield their flavors.
I always sauté my stock ingredients before adding the water to get some color on them and to bring out their flavors.
You don’t need to simmer your stock forever. At some point, the flavor of the vegetables is gone and you’re not going to get any more out of it (taste a vegetable and see!).
Allow a cooked stock to settle a few minutes before straining so that miscellaneous matter can fall to the bottom. On the other hand, don’t let it steep too long; certain herbs can turn bitter, especially fine-textured dried ones.
I sometimes simmer a strained stock to reduce it and concentrate the flavors—it takes about 30 minutes to reduce a cup of liquid to nothing, depending on how quickly it’s simmering.